The present invention claims the application benefit of the Korean Application No. P2001-069761 filed in Korea on Nov. 9, 2001, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a back light device and a method of manufacturing a back light device, and more particularly, to a direct-type back light device for a liquid crystal display (LCD) device and a method of manufacturing the same.
2. Discussion of the Related Art
In general, display screens of ultra thin-sized flat panel display devices having a thickness of several centimeters or less, and are commonly used as monitors for notebook computers, spacecraft, and aircraft. The display devices include a back light provided at a rear of a liquid crystal panel that is commonly used as a light source. However, the back light is inefficient because of its weight, power consumption, and overall thickness. The back light is formed of parallel cylindrical luminescent lamps, and may be classified into two difference categories: direct-type and light guiding plate-type.
In the direct-type back light device, luminescent lamps are arranged in parallel on a flat panel. However, a minimum distance between the luminescent lamps and the liquid crystal panel must be maintained in order to prevent an image of the luminescent lamps from being displayed onto the liquid crystal panel. In addition, a light scattering system must be provided for uniform light distribution. Accordingly, the direct-type back light device has a relatively large overall size. With the advent of large-sized display panel devices, a light-emitting area of the back light device must be increased. Accordingly, the direct-type back light device and light scattering system must also increase, wherein the light-scattering system should have a sufficient thickness to maintain a flat light-emitting area.
In the light guiding plate-type back light device, fluorescent lamps are provided along an outside periphery of a flat panel to disperse light using a light guiding plate. However, luminance is relatively low since the fluorescent lamps are provided along the outside periphery and the light must pass through the light guiding plate. In addition, advanced optical design and processing technologies are required to provide uniform distribution of luminous intensity.
The direct-type back light device and the light guiding plate-type back light device each have their own unique problems. For example, a direct-type back light device is commonly used for LCD devices such as monitors for personal computer or television where brightness of an image is more important than an overall thickness of the LCD device. On the other hand, a light guiding plate-type back light device is commonly used for LCD devices such as notebook computers where overall thickness of the LCD device is critical.
FIG. 1 is a perspective view of a direct-type back light device according to the related art. In FIG. 1, the direct-type back light device includes a plurality of luminescent lamps 1, an outer case 3 that fixes and supports the luminescent lamps 1, and a light scattering system 5a, 5b and 5c arranged between the luminescent lamp 1 and a liquid crystal panel (not shown).
The light scattering system prevents an image of the luminescent lamps 1 from being displayed onto a display screen (not shown), and provides a light source having uniform bright distribution. To enhance a light scattering effect, a plurality of diffusion sheets and a plurality of diffusion plates are arranged between LCD panel and luminescent lamps. The outer case 3 includes a reflecting plate 7 disposed on an interior side and is arranged to focus light emitted from the luminescent lamps 1 on a display part of the LCD panel (not shown), thereby enhancing light efficiency. The luminescent lamps 1 are commonly referred to as cold cathode fluorescent lamps (CCFLs) and function as a light source of an LCD device, when a power source is applied to electrodes 9a and 9b that are arranged at opposite ends of the luminescent lamps 1. The opposite ends of the luminescent lamps 1 are inserted to holes formed on opposing sides of the outer case 3.
However, the back light device according to the related art is problematic. For example, since only the opposite ends of the luminescent lamps 1 are fixed to the outer case 3, the luminescent lamps 1 may be damaged by external heat or sudden impact.
Accordingly, the present invention is directed to a back light device and a method of manufacturing a back light device that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a direct-type back light device in which luminescent lamps are securely fixed.
Another object of the present invention is to provide a direct-type back light device having uniform luminance.
Another object of the present invention is to provide a method of manufacturing a direct-type back light device in which luminescent lamps are securely fixed.
Another object of the present invention is to provide a method of manufacturing a direct-type back light device having uniform luminance.
Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, a direct-type back light device includes a plurality of luminescent lamps, a rectangular frame having holes formed along opposing sides with the luminescent lamps inserted into the holes, a reflecting plate formed at a bottom surface of the rectangular frame, and at least one lamp holder attached to the reflecting plate and supporting the luminescent lamps.
In another aspect, a direct-type back light device includes a plurality of luminescent lamps, a rectangular frame having holes formed along opposing sides with the luminescent lamps fixed and supported within the holes, a reflecting plate formed at a bottom surface of the rectangular frame, a light scattering system formed at a top surface of the rectangular frame, at least one protrusion fixed to the reflecting plate and supporting the light scattering system, and at least one lamp holder attached to the reflecting plate and supporting the luminescent lamps.
In another aspect, a method for manufacturing a direct-type back light device includes providing a reflecting plate at a bottom surface of a rectangular frame, attaching at least one lamp holder to the reflecting plate, and inserting a plurality of luminescent lamps into holes of the rectangular frame, wherein the at least one lamp holder contacts a surface of each of the plurality of luminescent lamps.
In another aspect, a method of manufacturing a direct-type back light device includes providing a reflecting plate at a bottom surface of a rectangular frame, attaching at least one lamp holder to the reflecting plate, inserting a plurality of luminescent lamps into holes of the rectangular frame, attaching the plurality of luminescent lamps to the at least one lamp holder, attaching at least one protrusion to the reflecting plate, providing a light scattering system at a top surface of the rectangular frame, wherein the at least one protrusion supports the light scattering system.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.